This disclosure generally relates to systems and methods for providing feedback to a pilot indicating that a flight parameter has exceeded constraints for proper operation during flight of a rotorcraft.
It is known to provide visual indicators in a cockpit for providing feedback to a helicopter pilot. However, in some cases the pilot may be distracted while flying the helicopter and may not notice a visual indicator indicating that a flight parameter (such as rotor-induced vibration level, airspeed, bank angle, icing accumulation, etc.) has exceeded constraints for proper operation.
For example, the loads in the rotor system of a helicopter may vary widely as a function of airspeed and aircraft gross weight. (As used herein, the term “rotor system” should be construed broadly to encompass one or more rotors operatively coupled to one or more engines by components configured to drive rotation of the rotor(s).) At certain combinations of airspeeds and loads, airframe vibration can be significant. It is known to measure alternating stress loads at each rotor of a twin-engine, tandem rotor helicopter by means of an electromechanical transducer, which provides an indication (called a cruise guide indicator) of rotor loading on the pilot instrument panel. The cruise guide indicator system gives the pilot a visual indication of actual loads imposed on critical components of the helicopter dynamic system. In a twin-engine, tandem rotor helicopter, the cruise guide indicator system measures forward and aft oscillatory loads transmitted from rotor systems to the airframe. (As used herein, the term “airframe” includes the fuselage and the cockpit structure.) The cruise guide indicator can provide a warning to the pilot to either decrease airspeed or reduce the severity of maneuvers to minimize loads in excess of the endurance limit of the dynamic components. Currently, there is no cueing from the cruise guide indicator to the pilot when exceedances for high loads are encountered beyond the visual display of a red indicator. Partially as a result of this, in practice the flight envelope of the helicopter may be restricted. For example, the gross weight of the helicopter at take-off may be restricted. This affects the full productivity and value of the helicopter to be realized by operators.
It would be desirable to provide improved systems and methods for cueing a helicopter pilot when a measured flight parameter exceeds an operating constraint.